Once More on a New Chassis

Even though American self propelled artillery lay dormant for a long time, the Americans were the first nation to enter the war with an existing SPG. This was the GMC T12, built on a halftrack chassis. The halftrack SPGs were a necessary compromise, but they allowed to quickly saturate American units with motorized artillery. Production of analogous SPGs on fully tracked chassis began in 1942. This approach proved fruitful, and by the spring of 1943 the Americans not only caught up to the Germans in SPGs but took the lead in some aspects. However, there were areas where they never managed to catch up. This is mostly true for heavy self propelled guns, but this is the Americans' own fault. Their answer to German heavy SPGs only went into battle towards the end of the war in Europe and the GMC M40 was only standardized in May of 1945.

Extra Ammo

 "July 29th, 1944
#522883

Experience in combat showed that the amount of ammunition carried in the T-34-85 (56 rounds) and IS-2 (28 rounds) is insufficient.

The NIBT Proving Grounds determined that it is possible to extend the T-34-85's ammunition racks by 15 rounds and the IS-2's by 3 rounds.

KV-1S Planetary Turning Mechanism

 "January 7th, 1943

In October and November of 1942 factory #100 developed and built a planetary turning mechanism designed by Engineer Lieutenant-Colonel A.I. Blagonravov. The report on the trials performed in the KV-1S tank is attached, we ask you to review it.

The Most Numerous Heavy SPG

Soviet heavy SPGs were initially designed to combat fortifications. When the war came, there turned out to be a much larger variety of targets for them. Wartime heavy SPGs were very different from what was initially envisioned. The Red Army needed universal vehicles that could both fight powerful fortifications and enemy heavy tanks. One of these vehicles was the ISU-152, a replacement for the SU-152 on the IS tank chassis. The ISU-152 became the most numerous heavy SPG in history.

The Last 76 mm Hole Punch

Armament and vehicles become obsolete quickly in war. This is caused by rapid development of both new types of weapons and defenses. This can be seen in the history of WW2. It's easy to see progress if you compare what the belligerents were using at the start of the war and what they were using in 1945. This applied to all aspects of the tanks: chassis, engines, observation devices, armour, and of course the armament. Tank armament evolved rapidly during the war. This evolution was directly linked to the growth of armour protection. Early war tanks could be defeated with a heavy machine gun, but towards the end gunners had to crack open mobile pillboxes with 150-200 mm of armour. This required rapid development of anti-tank guns.

Warspot Article: T-34 on Tour

The British received a lot from the USSR during the war, including raw materials and samples of vehicles and technology. A T-34 tank was one such sample. The tank sent in 1943 was not the latest in Soviet armoured vehicles, but still allowed the British to learn a lot about Soviet tank design. Read what conclusions the British made in my latest article on Warspot.net.

Big Self Propelled Caliber

Unlike SPGs armed with light or medium caliber guns, the British and Americans had a harder time with heavier weapons. This is strange, since SPGs were initially envisioned to mechanize heavy artillery. The British stalled completely in this direction and work did not progress past several prototypes. The Americans fared a little better. The first production vehicles appeared in the fall of 1942 and went into action in the summer of 1944. This was the Gun Motor Carriage M12, the first American SPG with a heavy gun. This article will cover this vehicle's complex fate.

Armoured Long Livers

 "Order of the Minister of the Armed Forces to the Commander of the Armoured and Mechanized Forces, Marshal of the Armoured Forces P.S. Rybalko on using unneeded armoured vehicles and spare parts for them

#452102
June 10th, 1947

Minister of the Armed Forces General of the Army comrade Bulganin permitted the use of unneeded armoured vehicles and spare parts for them in the following manner:

• 131 MK-3 [Valentine] tanks, 63 SU-122 SPGs and 282 SU-85 SPGs in need of repairs are to be converted into prime movers for use in the Armoured and Mechanized Forces instead of tractors.
  Functional SU-85 SPGs can be used for training and converted into prime movers as they break down.

The Zenith of AA Machine Guns

The USSR began working on the issues of protecting armoured vehicles from air attack in the early 1930s. The first plans were to create specialized self propelled anti-aircraft guns, but work on these topics did not pan out. Instead, the Red Army received tanks with AA machine gun mounts. This mount was developed at experimental factory #185. It was accepted into service as the P-40 in 1935 and entered production a year later. M.A. Shufrin was the lead engineer on this project. Ironically, his initials were rarely seen in association with factory #185, even though this was one of the few products of factory #185 that truly saw widespread use. Mass production of the mount began in 1937. Variants were installed on the T-26, BT-7, T-28, and T-35. At its inception it was the best anti-aircraft gun mount in existence. It allowed the DT machine gun installed on it to rotate a full 360 degrees. The DT machine gun was equipped with AA sights.

The KV-1 was the only new generation Soviet tank equipped with an AA machine gun, although it was not used frequently.

Mobile American Howitzer

The American army had a relatively small amount of armoured vehicles on hand at the start of WWII. Just over two years of neutrality proved enough to fully prepare for war. The American army had an impressive amount of light and medium tanks by December of 1941. They had so many tanks that they were also able to supply the British and offer significant help to the USSR. By the time the United States entered WWII they also had their first SPGs. At first these were built on halftrack chassis, but half a year later fully tracked vehicles became available. One of them was the HMC M7, better known under the British designation Priest. This was the most common self propelled howitzer of the war and it remained in service for decades after.